pname is a symbolic constant indicating
which parameter is to be set (see Table 2.8).
In the vector versions of the commands,
params is a pointer to a group of values to which to set the indicated
parameter.
The number of values pointed to depends on the parameter being set.
In the non-vector versions, param is a value to which to set
a single-valued parameter.
(If param corresponds to a multi-valued parameter,
the error INVALID_ENUM results.)
For the Material command,
face must be one of FRONT,
BACK, or FRONT_AND_BACK,
indicating that the property name of the front or back material,
or both,
respectively,
should be set.
In the case of Light,
light is a symbolic constant of the form LIGHTi,
indicating that light i is to have the specified parameter set.
The constants obey .

Table 2.8
gives,
for each of the three parameter groups,
the correspondence between the pre-defined constant names and
their names in the lighting equations,
along with
the number of values that must be specified with each.
Color parameters specified with Material and Light
are converted to floating-point values (if specified as integers)
as indicated in Table 2.6 for signed integers.
The error INVALID_VALUE occurs if a specified lighting
parameter lies outside the allowable range given in Table 2.7.
(The symbol ``'' indicates the maximum representable magnitude
for the indicated type.)

Table 2.8: Correspondence of lighting parameter symbols to names.
AMBIENT_AND_DIFFUSE is used to set and
to the same value.

The current model-view matrix is applied to the position
parameter indicated with
Light for a particular light source when that position is specified.
These transformed values are the values used in the lighting equation.

The spotlight direction is transformed when it is specified
using only the upper leftmost 3x3 portion of the model-view
matrix. That is, if is the upper left 3x3 matrix taken
from the current model-view matrix M, then the spotlight direction

is transformed to

An individual light is enabled or disabled by calling
Enable or Disable
with the symbolic value LIGHTi (i is in the range 0 to n-1,
where n is the implementation-dependent number of lights).
If light i is disabled,
the ith term in the lighting equation is effectively removed from the
summation.